Group III-V compound semiconductors such as, for example, GaN and AlGaN, are widely used for optoelectronics and electronic devices owing to many advantages such as, for example, a wide and easily adjustable band gap energy.
In particular, light-emitting devices such as light-emitting diodes or laser diodes using group III-V or II-VI compound semiconductors may realize various colors of light such as, for example, red, green, and blue light, as well as ultraviolet light, via the development of device materials and thin-film growth technique, and may also realize white light having high luminous efficacy via the use of a fluorescent material or by combining colors. These light-emitting devices have advantages of low power consumption, a semi-permanent lifespan, fast response speed, good safety, and eco-friendly properties compared to existing light sources such as, for example, fluorescent lamps and incandescent lamps.
Accordingly, the application of light-emitting devices has been expanded to a transmission module of an optical communication apparatus, a light-emitting diode backlight, which may substitute for a cold cathode fluorescent lamp (CCFL) constituting a backlight of a liquid crystal display (LCD) apparatus, a white light-emitting diode lighting apparatus, which may substitute for a fluorescent lamp or an incandescent bulb, a vehicle headlight, and a signal lamp.
In such a light-emitting device, a light-emitting structure, which includes an undoped semiconductor (un-GaN) layer, a first conductive semiconductor (n-GaN) layer, an active (MQW) layer, and a second conductive semiconductor (p-GaN) layer, may be formed over a substrate, which is formed of, for example, sapphire, and a first electrode and a second electrode may be disposed respectively on the first conductive semiconductor layer and the second conductive semiconductor layer.
In the light-emitting device, electrons injected through the first conductive semiconductor layer and holes injected through the second conductive semiconductor layer meet each other, thereby emitting light having energy determined by the inherent energy band of a constituent material of the active layer. The light emitted from the active layer may be changed according to the composition of the constituent material of the active layer, and may be blue light, ultraviolet (UV) light, deep UV light, or light of any other wavelength range.
FIG. 1 is a cross-sectional view of a conventional light-emitting device package, FIG. 2a is a view illustrating the area “A” of FIG. 1 in detail, and FIG. 2b is a plan view illustrating the area “A” of FIG. 1.
In the conventional light-emitting device package 100, a first lead frame 121 and a second lead frame may be disposed on a package body 110, and reflective layers 131 and 132 may be disposed respectively on the surfaces of the first lead frame 121 and the second lead frame 122.
The package body 110 may be provided with a cavity structure, and a light-emitting device 10 may be disposed on the bottom surface of a cavity. The light-emitting device 10 may be electrically connected to the first lead frame 121 and the second lead frame 122. This electrical connection may be realized via a conductive adhesive 140.
The cavity may be filled with a molding portion 160, which includes phosphors 165.
In FIG. 2a, when the light-emitting device 10 is a flip-chip type light-emitting device, the conductive adhesive 140, which electrically connects the first lead frame 121 and the second lead frame 122 to the light-emitting device 10, may be of a bump type.
At this time, horizontal force Fh and vertical force Fv may be generated from the first lead frame 121 and the second lead frame 122, and the vertical force Fv to be transferred to the light-emitting device 10 may be relatively large. In addition, when the light-emitting device 10 is flip-chip bonded, the bump-shaped conductive adhesive 140 may directly come into contact with a light-emitting structure so that the above-described vertical force Fv may be transmitted to the light-emitting structure, thus causing damage to the light-emitting structure.
In FIG. 2b, the light-emitting device 10 on the first lead frame 121 and the second lead frame 122 is illustrated by the dotted line. The vertical force Fv of FIG. 2a may be greater than first horizontal force Fh1 and second horizontal force Fh2 transferred from the first lead frame 121 to the light-emitting device 10.
In the flip-bonding type light-emitting device described above, it is necessary to prevent the light-emitting structure from being damaged by the force transferred to the bump-shaped conductive adhesive.